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What is CYFRA 21-1 test?

CYFRA 21-1 is a soluble fragment of the cytokeratin-19 protein, a type of cell surface protein whose expression doesn’t change in cancer cells - it is not increased or decreased. However, as more cells are present in a tumour or cancer (than a healthy tissue), a person with cancer would have more amount of cytokine 19. 

Since it is found in serum, CYFRA 21-1 can be used to detect the amount of cytokine 19 and hence the presence of cancer. Although CYFRA 21-1 is present in most body tissues, it is present in high amount in lungs. Thus, it is considered an important marker for lung cancer.

Studies suggest that high levels of CYFRA 21-1 are found in the serum of lung cancer patients, especially those with non-small cell lung cancer. 

A CYFRA 21-1 test is hence used to diagnose non-small cell lung cancer.

Non-small cell lung cancer is a relatively less aggressive form of lung cancer, which shows larger cell structures than the more aggressive small cell lung cancer.

Lung Cancer originates when there is an uncontrollable growth of abnormal cells anywhere in the lungs. Cancer cells do not mature like normal functioning cells and tend to divide far more rapidly, thus forming a mass of unwanted cells (tumour). Initially, the lump of cells may remain localised, but there is always a chance that cancer could spread to other areas of the body such as nearby organs and lymph nodes. Individuals having a family history of lung cancer are at higher risk of getting this disease. Other risk factors that increase one’s predisposition to the disease are as follows:

  • Long-term exposure to air pollution
  • Presence of pulmonary fibrosis
  • Exposure to radiation (during radiation therapy)
  • Smoking
  • Prolonged exposure to carcinogenic substances such as arsenic and cadmium
  • Family history
  • Presence of HIV or tuberculosis infection
  1. Why is a CYFRA 21-1 test performed?
  2. How do you prepare for a CYFRA 21-1 test?
  3. How is CYFRA 21-1 test performed?
  4. What do CYFRA 21-1 test results mean?

CYFRA 21-1 test is used to diagnose both primary (originating in the lungs) and metastatic (spreading type) lung cancer. It also helps to check for the stage of cancer and helps doctors in determining the form of treatment to be followed based on the extent of the disease.

Common symptoms associated with lung cancer are:

Additionally, CYFRA 21-1 test helps look for recurrence of lung cancer in an individual who has already been diagnosed with it once. 

You will be advised to come in hydrated for the test as it would help in easy withdrawal of the blood sample. For some individuals, the doctor may recommend fasting for several hours before the test. Tell your doctor if you are taking any medicines or health supplements.

A doctor or laboratory technician will collect a small amount of blood from a vein in your arm using a sterile needle. You may feel no pain from the needle or just a quick sting or pinch.

Some risks associated with this test are: 

However, these risks can easily be avoided if proper precautionary measures are taken.

Normal results:

The reference range for this test across all age groups is considered to be >100 kU/L, which indicates normal or negative results. 

Abnormal results:

Abnormal results indicate that the level of CYFRA 21-1 is elevated in your blood, which would confirm the presence of lung cancer. The higher the level of CYFRA 21-1, the more advanced the disease stage is likely to be. A high level may also mean that the patient is at a higher risk of treatment failure.

Disclaimer: All results must be clinically correlated with the patient’s complaints to make a complete and accurate diagnosis. The above information is provided from a purely educational point of view and is in no way a substitute for medical advice by a qualified doctor.

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  5. American Lung Association [internet]; Lung Cancer Tumor Testing
  6. Weiskopf B, et al. Cyfra 21-1 as a biological marker of non-small cell lung cancer. Evaluation of sensitivity, specificity and prognostic role. Chest. 1995 Jul;108(1):163-9.